X11 forwarding, how to change strange colors?

Question

I have an old SUN Solaris 2.5 box, which controls very important hardware from the 1990s. I need this old thing because a replacement would cost me 80 kEuros (!). The OS of the SUN does not have ssh, and even not utilities like pkgadd or compilers ... ;-)

Since the GPU has become somewhat 'weak' (I already lost one GPU card) I sent the X11 graphics of the program, which controls the hardware, to a Lubuntu 14.04 (64Bit) box, via 'setenv DISPLAY IPaddress:0.0' (this is sometimes referred as to be X11 forwarding). Everything works quite well, in particular the system has become very fast (!). By the way, on the Ubuntu box, I merely had to install telnetd and to remove this '-nolisten' via a config file inside /etc/lightdm/lightdm.d.config/.

So far, so good. There is one severe problem now: the windows on the Ubuntu desktop (there are several windows) have different colors in comparison to the 'normal' case where the SUN runs the graphics (no forwarding). Some important text appears in a very dark gray color on a black background (text color rgb: 3/3/3 on 0/0/0 background). The general window color has a rgb value of 114/159/255 (medium purple1), which also is strange. Overall, very important text cannot be read, which is bad.

Obviously, there is a mismatch of color understanding between the Ubuntu box from today and the SUN from the 1990s, no wonder.

I tried out the following things without success:

• Playing around with the desktop themes in Lubuntu
• Changing the color depth of the Ubuntu system via a xorg.conf file
• Xephyr and xnest with standard parameters
• Changing color values in this rgb.txt file in /usr/share/X11/ on the Ubuntu box

How can I change the colors, can somebody help me? Note that under Windows2000 and Xming things work very well. However, I don't want to use Windows.

I have in mind to …

• use an older Linux system, which still understands the SUN from the 1990s,
• use a different window manager like fvwm,
• ...

Thanks for some comments.

Answer 1

I'm proud to offer a solution myself!

Everything makes sense, in particular when considering Linux systems of today on the one hand, and old SUN workstations from the 1990s on the other: both they do not 'understand' each other with respect to X11 colors and therefore the recent Linux system needs to combine old with the old, as follows … :

One needs to start Xephyr in 8 bit resolution first because the SUN understands only 8 bit:

Ubuntu > Xephyr :1 -ac -br -screen 1920x1080x8 -reset -terminate &

So far, we have an X server with 8 bit colors. Next we need a window manager that still understands the 'old way' of X forwarding. Let's use therefore fvwm and start it in the latter X server:

Ubuntu > DISPLAY=:1 fvwm &

Then we do telnet to the SUN. Before, we have to add first the IP address of the SUN to xhost on the Ubuntu box:

Ubuntu > xhost + IPaddress_SUN

Then ...

Ubuntu > telnet IPaddress_SUN

... and login on the SUN.

On the SUN we type:

SUN > setenv DISPLAY IPaddress_Ubuntu:1.0

Note, that one needs to choose the correct X server on the Ubuntu box by typing ...:1.0

Then one can start the application

SUN > <application_name>

That's it. Thanks for some comments and credits.

PS: One cannot use the window manager 'xfce4-session', it simply displays wrong colors.